Devices for removing particulate contaminants from motor fuel are known in the art, and include gasoline fuel filters as well as diesel fuel filters. Principally these devices are designed to remove particles from the fuel to prevent the contaminants from entering the engine, and in the case of a diesel engine to prevent the contaminant from obstructing the fuel injectors of the common diesel engine.
Further, it is known that water sometimes finds its way into fuel storage tanks and tanks mounted on vehicles. Often, this water is removed by providing a drain bowl at the lowest point in the fuel line, or at the lowest point in the fuel tank. Water is then periodically drained from this fuel bowl to remove the water from the fuel. Fuel bowls have the disadvantage of typically being located in a portion of the vehicle which is difficult to reach, as the fuel bowl must be located at the lowest point of travel of the fuel line. Also, the operator is typically unaware that the bowl contains separated water unless a visual inspection is made. Visual inspections are often ignored and are hampered by the inevitable accumulation of dirt and grime on the outside of the bowl making an accurate inspection difficult. The problems associated with water in engine fuel have been known for many years. Unfortunately, since no warning mechanism alerted the operator when the bowl was fill of water, most engines were operated with the bowl full and water reaching the engine from time to time. Misfiring, rough operation and severe engine damage often resulted.
Other techniques for removing water from fuel include the use of additives to the fuel which allow the water to mix with the fuel and be successfully burned by the engine. These additives have the disadvantage of being expensive and requiring the additional step of combining the additive with the fuel.
Today, with the increased use of diesel engines for motor vehicles including heavy duty trucks and common passenger automobiles, as well as the continued use of diesel engines in stationary locations such as for generators and water irrigation systems, the need for purified diesel fuel has increased. Also, the amount of water and bacterial contaminants found in diesel fuel has increased in recent years. This problem is especially acute in remote areas and in underdeveloped regions of the world.
The growth of bacteria in diesel fuel contaminated with water, is a serious problem. This bacteria forms a gelatinous scum or film which greatly impairs the efficient functioning of the modern diesel engine. Removal of this bacteria can be accomplished by draining water from a fuel bowl. Additionally, an antibacterial agent or bacteria killing compound can be added to the fuel. Antibacterial agents have the disadvantage of being expensive and requiring the additional step of adding the agent to the fuel.
Devices for separating water from fuel are known in the art. U.S. Pat. No. 4,017,397 issued Apr. 12, 1977 to Copeland is an example of a filter device which allows separated water to be removed from a filter type device. The Copeland device is an example of a type of fuel water separator which is characterized by the following disadvantage: the level of water present in the separator is not automatically reported to the operator. A glass bowl or other device is therefore required, and manual inspection of the device at regular intervals is necessary to determine when water should be removed from the device. The inspection of such a device is inconvenient and may be hindered by the accumulation of dirt or oily substances on the outside of the glass bowl.
U.S. Pat. No. 4,276,161 issued June 30, 1981 to Matsui, et al. is an example of a fuel filter of the type provided with a water level detecting means. In the Matsui device a fuel filter has an electrode at the bottom part of a casing forming a detecting gap with the metal body of the casing. When separated water reaches a predetermined level, a low resistance condition between the electrode and the casing is detected. The Matsui device is an example of the type of device which has electric wiring passing into the filter at its lowermost point. This type of device has the disadvantage of requiring removal of the wiring to change the filter element, running the risk of tangling or severing the wires. Another disadvantage of having wiring entering the filter at the lowest point of the filter center is the degenerative effect petrochemical distillates have on rubber based wiring insulation. Should the insulation on the wiring become frayed or cracked, a short circuit and erroneous reading could result. The use of non-rubber based insulation can typically overcome this problem, but these compounds may be inflexible at low temperatures which may complicate the changing of the filter elements.
These and other disadvantages of the devices known in the prior art leave room for improvement in the field of fuel purification and contaminant removal. Consequently, there is a need for an improved fuel water separator allowing efficient separation of water and associated bacterial contaminants from fuel. Simplified removal of the separated water from the device, along with easy removal of air pockets or voids within the device and a simple to operate automatic water level detection mechanism which does not hinder the removal and replacement of the filter cartridge is required. Further, a fuel separator having the ability to alert the operator of a high restriction condition within the device is required.
As the quality of available fuel has decreased, the useful life of filter elements has also tended to decrease. As the filter elements become dirty with foreign matter, the passage of fuel through the filter is impeded. Most engine manufacturers require that fuel filters be replaced at scheduled intervals to prevent engine damage. The damage done to an engine by operation with contaminated fuel is well known, but the exact useful life of a filter element has heretofore been difficult to determine.
As the amount of foreign matter found in fuel can vary widely between sources of supply, a vehicle operated over the road may acquire a load of "bad fuel" at certain locations, thus accelerating the accumulation of foreign matter in the fuel filter. This condition may be aggravated in engines operated off of the highway as in these locations the storage facilities for fuel may be primitive. Therefore, simply replacing the fuel filter at regular intervals may result in the operation of an engine with a badly restricted filter or may result in the disposal of a filter which still has significant useful life.
Indication of the state of restriction of the filter element has been attempted in the past. One common solution has been to place a visual restriction indicator on the head of the fuel separator or oil filter. An example of this type of device would be a glass tube with a sliding piston inside, wherein the ends of the tube are exposed to the vacuum drop across the filter element. Movement of the piston indicates a certain vacuum drop. The problems described above with respect to visual inspection of water levels apply to the visual inspection of this type of device. For example, grease or dirt may cover the tube making a reading difficult. Further, the engine must be in operation for the common restriction indicator to be operable, as a vacuum drop across the filter is only present during engine operation.
In a vehicle having such a restriction indicator, the operator must usually leave the controls of the vehicle, with the engine running, to inspect this type of device. This may present serious safety concerns for the operator and the vehicle. Therefore, there has long been a need for a fuel separator which will detect and indicate to the operator when a fuel filter element becomes unsatisfactorily restricted. There is particularly a need for a filter restriction indicator which will immediately report to the operator should the filter element become clogged during operation of the engine, with the restriction condition indicated to the operator even if the operator is located remotely from the engine.